Base: fix warnings from code analysers:

* replace some C-style casts with static_cast
* remove unneeded destructors
* define default copy-constructor and assignment operator

src/Base/Writer.h

@@ -134,6 +134,10 @@ protected:
 
     bool forceXML;
     int fileVersion;
+
+private:
+    Writer(const Writer&);
+    Writer& operator=(const Writer&);
 };